Xindus was an inhabited planet in the Delphic Expanse and the homeworld of the Xindi. It was the only planet in its solar system.
The planet was geologically unstable and was destroyed in 2033 when, at the height of the Xindi Civil War, the Reptilians and Insectoids detonated large weapons beneath the eight largest seismic fissures of the planet. While five of the Xindi species escaped this destruction, the Xindi-Avians lacked the ability to flee the planet and were wiped out. The five surviving species spread out across the Expanse, settling on various planets. (ENT: "The Shipment")
In 2153, Enterprise NX-01 discovered an asteroid field nearly 80 million kilometers long orbiting a yellow-orange star. This was what remained of Xindus. (ENT: "The Xindi", "Azati Prime")
Although the remains of this planet appear as early as third season opener "The Xindi", the planet wasn't named until the third last episode of that season, "The Council".
In the script of "The Xindi", the debris from Xindus is described as "a vast, cigar-shaped debris field stretching in a partial around [a] star."